1. Field of the Invention
The present invention relates to a digital video disk ROM interface. More particularly, the present invention relates to a digital video disk ROM (DVD-ROM) interfacing apparatus for controlling data transmission from a digital video disk (DVD) signal processor to an ATAPI interface device, and a method thereof.
2. Description of the Related Arts
A digital video disk (DVD), which is a medium for storing moving images and sound signals at high density, has a storage capacity of several times as large as that of a conventional compact disk (CD). The above DVD having a large storage capacity can also be used as an auxiliary memory device of a computer.
The DVD-ROM system includes servo mechanisms (automatic devices that use feedback to govern the physical position of a mechanical element such as a read/write head) for reading a signal recorded on a disk by controlling the rotation of a spindle motor, the tracking of a pickup on the disk, the laser output and the focusing of the laser beam output from the pickup; a DVD signal processor for demodulating and decoding the read signal to recover an original data; and an advanced technology attachment packet interface (ATAPI) device for interfacing the DVD signal processor with a data processor such as a personal computer.
FIG. 1 is a block diagram of a typical ATAPI device. An ATAPI device 20 includes a DVD interface 22 for inputting reproduced data from a DVD signal processor 10 under the control of a microcontroller 12, a memory controller 24 for controlling a memory 14 to store or read the data input from the DVD interface 22 in or from the memory 14, and a host interface 26 for receiving an operation commands and other control signals from a host computer through an ATAPI bus 16 and transmitting the received commands and control signals to the microcontroller 12 and the DVD interface 22 and the reproduced data to the host computer 18 through the ATAPI bus 16.
Now referring to FIG. 1A, the elements shown below in FIG. 3 are part of a system to deliver video/audio data to a user. The DVD-ROM system 30 processes data stored on a DVD and transmits the processed data to the host computer 18. The DVD-ROM system 30 may be remotely located from the host computer 18 in the manner that a server is remotely located from a client computer. One or more computer outputs the processed data in the form of video and/or audio signals which may be viewed/listened to by a user on one or more video output 33 and one or more audio outputs 31, 35. Input and output devices associated with the DVD-ROM system, computer and display output devices are suitably interfaced with the interconnections made and required for operation.
Meanwhile, according to an interface between a CD signal processor and the a CD-ROM decoder of a conventional CD-ROM system, data is transmitted unilaterally from the CD signal processor to the CD-ROM decoder. However, under such an interfacing scheme, the CD-ROM decoder receives data regardless of the state of its buffer memory, which causes difficulties in effective control of the buffer memory of the system. To make matters worse, the unilateral interfacing scheme may cause a malfunction of the system, especially in a system operating at high speed.
Accordingly, the DVD-ROM system employs a handshaking scheme so that the DVD signal processor 10 transmits data only when there is a request from the ATAPI interface device 20. Here, only one byte of data for one data request signal is transmitted.
Referring to FIG. 2, when one block of data is to be transmitted from the DVD signal processor 10 to the ATAPI interface device 20, a top of signal (TOS) is input from the DVD signal processor 10 to a DVD interface 22 of the ATAPI device 20 as a block start signal.
Subsequently, the microcontroller 12 checks the state of an external memory 14 which functions as a buffer. When the memory 14 has enough space to store data, the DVD interface 22 transmits a data requesting signal data.sub.-- req to the DVD signal processor 10. When the DVD signal processor 10 detects a falling edge of the data requesting signal, the DVD signal processor 10 outputs one byte of data together with a data transmission acknowledgment signal data.sub.-- ack to the ATAPI device 20. Upon receiving the rising edge of the data transmission acknowledgment signal data.sub.-- ack, the ATAPI device 20 deactivates the data request signal data.sub.-- req. Then, the ATAPI device 20 receives the transmitted data DATA0 in synchronicity with the falling edge of the data transmission acknowledgment signal data.sub.-- ack Afterwards, a second data is input by transmitting the data request signal data.sub.-- req to the DVD signal processor 10, and such steps are repeatedly carried out to receive a plurality of data.
According to the above DVD interface of the conventional ATAPI device, the transmission efficiency is low and the burden of the microcontroller is excessively heavy since one data request signal data.sub.-- req is transmitted for one byte of data.